Yahoo Mail has re-enabled automatic email forwarding from one account to another, after it was previously disabled. It caused difficulty for users looking to migrate away from Yahoo after a massive data breach into its email service was revealed in September.
Yahoo on Friday wrote in a blog post that "auto-forward is enabled again for all Mail users. We apologize for the interruption".
Auto-forwarding is available on most popular email services, allowing users to try a new service without losing emails from their old address.
Yahoo said Yahoo Mail has been upgrading its platform over the last year. Email forwarding was temporarily disabled as part of this process, suggesting it wasn't disabled specifically because of the hacking revelations.
In September, Yahoo confirmed a data breach took place in 2014 that affected at least 500 million user accounts. It later said that a "state-sponsored actor" gained access to names, email addresses, telephone numbers, dates of birth, hashed passwords, and, in some cases, encrypted or unencrypted security questions and answers.
The mass data breach has thrown up red flags for Verizon, which is in the process of acquiring Yahoo for $4.83 billion.
Verizon has "a reasonable basis to believe right now that the impact is material, and we're looking to Yahoo to demonstrate to us the full impact," Verizon's general counsel said on Thursday.